Tektronix Keithley 4200A-SCS User Manual
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Tektronix Keithley 4200A-SCS User Manual

Source-measure unit
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Model 4200A-SCS
Source-Measure Unit (SMU)
User's Manual
4200A-SMU-900-01 Rev. A December 2020
*P4200A-SMU-900-01A*
4200A-SMU-900-01A

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  • Page 1 tek.com/keithley Model 4200A-SCS Source-Measure Unit (SMU) User’s Manual 4200A-SMU-900-01 Rev. A December 2020 *P4200A-SMU-900-01A* 4200A-SMU-900-01A...
  • Page 2 Model 4200A-SCS Source-Measure Unit (SMU) User's Manual...
  • Page 3 © 2020, Keithley Instruments Cleveland, Ohio, U.S.A. All rights reserved. Any unauthorized reproduction, photocopy, or use of the information herein, in whole or in part, without the prior written approval of Keithley Instruments is strictly prohibited. All Keithley Instruments product names are trademarks or registered trademarks of Keithley Instruments, LLC.
  • Page 4 Safety precautions The following safety precautions should be observed before using this product and any associated instrumentation. Although some instruments and accessories would normally be used with nonhazardous voltages, there are situations where hazardous conditions may be present. This product is intended for use by personnel who recognize shock hazards and are familiar with the safety precautions required to avoid possible injury.
  • Page 5 For safety, instruments and accessories must be used in accordance with the operating instructions. If the instruments or accessories are used in a manner not specified in the operating instructions, the protection provided by the equipment may be impaired. Do not exceed the maximum signal levels of the instruments and accessories. Maximum signal levels are defined in the specifications and operating information and shown on the instrument panels, test fixture panels, and switching cards.

  • Page 6: Table Of Contents

    Table of contents Introduction ......................1-1 Introduction .......................... 1-1 Source-measure unit (SMU) ....................1-1 Preamplifier .......................... 1-2 Ground unit (GNDU) ......................1-2 Connections and configuration ................2-1 Basic source-measure connections ..................2-1 SMU connections ........................2-2 Preamplifier local sense connections ..................2-11 Using the ground unit ......................
  • Page 7 Table of contents Model 4200A-SCS Source-Measure Unit (SMU) User's Manual Compliance ..........................3-17 Dual Sweep ..........................3-18 Force Range (Source Range) ....................3-19 List Values..........................3-19 Low Range ..........................3-19 Measure Current ........................3-19 Off Time ..........................3-19 On Time ..........................3-20 Overvoltage protection ......................
  • Page 8 Model 4200A-SCS Source-Measure Unit (SMU) User's Manual Table of contents Compliance limit for a SMU with a 4200-PA................4-6 Using minimum compliance ...................... 4-7 Operating boundaries ........................ 4-7 Preamplifier terminals and connectors ..................4-8 FORCE terminal ........................4-10 SENSE terminal ........................4-11 Preamplifier CONTROL connector ..................
  • Page 9 Table of contents Model 4200A-SCS Source-Measure Unit (SMU) User's Manual Eliminating oscillations ......................6-3 Low-current measurements ....................6-4 Leakage currents ........................6-5 Generated currents ........................6-5 Voltage burden .......................... 6-8 Noise and source impedance ....................6-9 Cable capacitance ........................6-10 Test system performance ......................

  • Page 10: Introduction

    Section 1 Introduction In this section: Introduction ................1-1 Source-measure unit (SMU)............. 1-1 Preamplifier ................1-2 Ground unit (GNDU) ..............1-2 Introduction This document provides information about the 4200-SMU, 4201-SMU, 4210-SMU, and 4211-SMU source-measure units and related instruments, including: • Connections and configuration (on page 2-1): Basic information on connecting source-measure units (SMUs), the preamplifier, and the ground unit to devices under test (DUTs), making test...

  • Page 11: Preamplifier

    Section 1: Introduction Model 4200A-SCS Source-Measure Unit (SMU) User's Manual The source of the SMU can be configured to sweep or step voltages or currents, or to output a constant bias voltage or current. There are medium-power and high-power source-measure units available. The 2 W medium-power SMUs are models 4200-SMU and 4201-SMU.

  • Page 12: Connections And Configuration

    Section 2 Connections and configuration In this section: Basic source-measure connections ......... 2-1 Test fixture and device under test (DUT) connections ... 2-20 Basic source-measure connections This section describes basic information on connecting source-measure units (SMUs), the preamplifier, and the ground unit to devices under test (DUTs). The 4200A-SCS is provided with an interlock circuit that must be positively activated for the high voltage output to be enabled.

  • Page 13: Smu Connections

    Section 2: Connections and configuration Model 4200A-SCS Source-Measure Unit (SMU) User's Manual SMU connections The following topics explain how to connect the source-measure units (SMUs) to the device under test (DUT). The SMU can be connected directly to the device under test (DUT) with triaxial cables using either local or remote sensing, as described in the following topics.
  • Page 14 Model 4200A-SCS Source-Measure Unit (SMU) User's Manual Section 2: Connections and configuration Triaxial cables Triaxial cables are supplied to make connections to the DUT (device under test). With preamplifiers installed, use the low-noise triaxial cables, which are terminated with 3-slot triaxial connectors on both ends.
  • Page 15 Section 2: Connections and configuration Model 4200A-SCS Source-Measure Unit (SMU) User's Manual SMU local sense connections The simplest method to connect SMUs to the device under test (DUT) is to use one SMU for each terminal of the device. When setting up a test, the FORCE terminal (center conductor) of the SMU is used to apply voltage or current to the device.
  • Page 16 Model 4200A-SCS Source-Measure Unit (SMU) User's Manual Section 2: Connections and configuration Basic device connections for SMUs The following figures show the basic connections to 2-terminal, 3-terminal, and 4-terminal devices. Notice that only the FORCE HI terminal of each SMU is connected to the device terminal. FORCE HI is the center conductor of the triaxial cable.
  • Page 17 Section 2: Connections and configuration Model 4200A-SCS Source-Measure Unit (SMU) User's Manual Figure 7: Four-terminal device connections to SMUs and preamplifiers Shielding and guarding Many test situations require that the device under test (DUT) be shielded or guarded (or both) to avoid detrimental effects caused by electrostatic interference, parasitic capacitance, system leakage currents, and so forth.
  • Page 18 Model 4200A-SCS Source-Measure Unit (SMU) User's Manual Section 2: Connections and configuration Figure 8: Device shielding Figure 9: Device shielding basic circuit 4200A-SMU-900-01 Rev. A December 2020...
  • Page 19 Section 2: Connections and configuration Model 4200A-SCS Source-Measure Unit (SMU) User's Manual To guard the device, connect the DUT shield to GUARD. GUARD is the inner shield of triaxial cable, as shown in the following figure. Figure 10: Device guarding Figure 11: Device guarding basic circuit 4200A-SMU-900-01 Rev.
  • Page 20 Model 4200A-SCS Source-Measure Unit (SMU) User's Manual Section 2: Connections and configuration Signal integrity To maintain signal integrity, especially at low current levels, consider the following when making signal connections between the 4200A-SCS instrumentation and the device under test (DUT): •...
  • Page 21 Section 2: Connections and configuration Model 4200A-SCS Source-Measure Unit (SMU) User's Manual Figure 12: Typical SMU connections Figure 13: Typical SMU COMMON connections schematic 2-10 4200A-SMU-900-01 Rev. A December 2020...

  • Page 22: Preamplifier Local Sense Connections

    Model 4200A-SCS Source-Measure Unit (SMU) User's Manual Section 2: Connections and configuration Preamplifier local sense connections The following figures show typical preamplifier connections using local sensing. Use a triaxial cable to make your connections as follows: • Connect preamplifier FORCE (center conductor of FORCE terminal) to DUT HI. •...

  • Page 23: Using The Ground Unit

    Section 2: Connections and configuration Model 4200A-SCS Source-Measure Unit (SMU) User's Manual Using the ground unit The ground unit (GNDU) provides convenient access to circuit COMMON through the GNDU FORCE terminal or the GNDU COMMON binding post terminal. The GNDU also has a SENSE terminal. The SENSE LO signal of each instrument installed in the 4200A-SCS is connected to the GNDU SENSE terminal.
  • Page 24 Model 4200A-SCS Source-Measure Unit (SMU) User's Manual Section 2: Connections and configuration Figure 17: Ground unit and SMU remote sense connections Ground unit and preamplifier local sense connections The following figure shows typical local sense connections using two preamplifiers, two DUTs, and the ground unit.
  • Page 25 Section 2: Connections and configuration Model 4200A-SCS Source-Measure Unit (SMU) User's Manual Figure 18: Ground unit and preamplifier local sense connections Figure 19: Ground unit and preamplifier local sense connections schematic Ground unit and preamplifier remote sense connections The following figure shows typical remote sense connections using two preamplifiers, two DUTs, and the ground unit.
  • Page 26 Model 4200A-SCS Source-Measure Unit (SMU) User's Manual Section 2: Connections and configuration Figure 20: Ground unit and preamplifier remote sense connections Figure 21: Ground unit and preamplifier remote sense connections schematic 4200A-SMU-900-01 Rev. A December 2020 2-15...

  • Page 27: Basic Smu Circuit Configuration

    Section 2: Connections and configuration Model 4200A-SCS Source-Measure Unit (SMU) User's Manual Basic SMU circuit configuration The basic SMU circuit configuration is shown in the following figure. The SMU is essentially a voltage or current source in series with a current meter, connected in parallel with a voltage meter. The voltage limit (V-limit) and current limit (I-limit) circuits limit the voltage or current to the programmed compliance value.
  • Page 28 Model 4200A-SCS Source-Measure Unit (SMU) User's Manual Section 2: Connections and configuration SMU terminals and connectors The locations and configuration of the SMU terminals are shown in the following figure. Basic information about these terminals is summarized below. Asserting the interlock allows the SMU and preamplifier terminals to become hazardous, exposing the user to possible electrical shock that could result in personal injury or death.
  • Page 29 Section 2: Connections and configuration Model 4200A-SCS Source-Measure Unit (SMU) User's Manual SENSE LO terminal The SENSE LO terminal is a miniature triaxial connector used to apply the SMU SENSE LO signal to the DUT in a full-Kelvin (remote sense) application. •...
  • Page 30 Model 4200A-SCS Source-Measure Unit (SMU) User's Manual Section 2: Connections and configuration PA CNTRL connector The PA CNTRL (preamplifier control) terminal is a 15-pin D-sub connector that provides both power and signal connections to the 4200-PA Remote Preamplifier. The preamplifier can either be mounted and connected directly to the SMU, or it can be connected to the SMU using a cable (4200-RPC-X) when mounted remotely.

  • Page 31: Test Fixture And Device Under Test (Dut) Connections

    Section 2: Connections and configuration Model 4200A-SCS Source-Measure Unit (SMU) User's Manual Test fixture and device under test (DUT) connections The recommended Keithley Instruments test fixture to use with the 4200A-SCS is the Model 8101-PIV Test Fixture. Test fixtures for the 4200A-SCS can be: •...

  • Page 32: Testing With More Than ±20 V

    Model 4200A-SCS Source-Measure Unit (SMU) User's Manual Section 2: Connections and configuration The Keithley Instruments Low Level Measurements Handbook provides an in-depth discussion on guarding and other techniques that are useful for building quality test fixtures. See the Learning Center on your 4200A-SCS for a copy of the Handbook. The 4200A-SCS functions on all current ranges and up to ±20 V without the interlock being asserted.
  • Page 33 Section 2: Connections and configuration Model 4200A-SCS Source-Measure Unit (SMU) User's Manual Triaxial cables are supplied to make connections to the device under test (DUT). With preamplifiers installed, use the low-noise triaxial cables, which are terminated with three-slot triaxial connectors on both ends.

  • Page 34: Setting Up Smus In Clarius

    Section 3 Setting up SMUs in Clarius In this section: Introduction ................3-1 Set up a simple project ............. 3-1 Configure a simple test ............3-3 Run a simple test ..............3-8 Operation Mode (SMU) ............3-9 SMU - all terminal parameters ..........3-16 SMU Test Settings ..............

  • Page 35: Add A Device And Test To The Project

    Section 3: Setting up SMUs in Clarius Model 4200A-SCS Source-Measure Unit (SMU) User's Manual To set up a test of BJTs: 1. Select Save to save your existing project. 2. Choose Select. 3. Select the Projects tab. 4. In the Filters pane, select Transistor. 5.

  • Page 36: Configure A Simple Test

    Model 4200A-SCS Source-Measure Unit (SMU) User's Manual Section 3: Setting up SMUs in Clarius To add a four-terminal MOSFET device and test to the project: 1. In the center pane, select Tests. 2. In the Filters pane, select Transistor and 4 Terminals. 3.
  • Page 37 Section 3: Setting up SMUs in Clarius Model 4200A-SCS Source-Measure Unit (SMU) User's Manual The connections selected in the Clarius software must accurately reflect the physical hardware connections when the test is executed. Incorrect terminal configurations can result in anomalous test results and device damage. The key parameters for each terminal are displayed near the terminal.

  • Page 38: Set The Key Parameters

    Model 4200A-SCS Source-Measure Unit (SMU) User's Manual Section 3: Setting up SMUs in Clarius Set the key parameters The Key Parameters are the most commonly used parameters for a terminal. To set the Key Parameters: 1. Select the field that you want to change. 2.

  • Page 39: Set The Test Parameters

    Section 3: Setting up SMUs in Clarius Model 4200A-SCS Source-Measure Unit (SMU) User's Manual Figure 32: Terminal Settings tab and Terminal Settings Advanced dialog box Set the test parameters In the Test Settings pane, you can set items such as: •...
  • Page 40 Model 4200A-SCS Source-Measure Unit (SMU) User's Manual Section 3: Setting up SMUs in Clarius To set up test parameters: 1. In the project tree, select the test. 2. Select Configure. 3. Select Test Settings in the right pane. Figure 33: Test Settings for a SMU test 4.

  • Page 41: Run A Simple Test

    Section 3: Setting up SMUs in Clarius Model 4200A-SCS Source-Measure Unit (SMU) User's Manual Run a simple test When you select Run, selected tests and actions at a lower level than the highlighted item in the project tree are executed, from top to bottom in the project tree. If you want to run an entire project, make sure the project name is highlighted.

  • Page 42: Operation Mode (Smu)

    Model 4200A-SCS Source-Measure Unit (SMU) User's Manual Section 3: Setting up SMUs in Clarius In the following example, only the gummel test runs. Even though the other tests are selected, they are not below the gummel test in the hierarchy. Figure 35: Run specific tests To run a test in Clarius: 1.

  • Page 43: Open Operation Mode - Smu

    Section 3: Setting up SMUs in Clarius Model 4200A-SCS Source-Measure Unit (SMU) User's Manual Figure 36: Stepping and sweeping example Open operation mode - SMU Open operation mode maintains a zero-current state at the terminal, subject to the maximum voltage compliance of the connected SMU.

  • Page 44: Voltage Segment Sweep Operation Mode

    Model 4200A-SCS Source-Measure Unit (SMU) User's Manual Section 3: Setting up SMUs in Clarius Figure 37: Example linear sweep The voltage sweep generates parametric curve data that is recorded in the Analyze pane. Voltage Segment Sweep operation mode When you select the Voltage Segment Sweep operation mode, the test increments through a series of constant voltage steps.

  • Page 45: Voltage List Sweep Operation Mode

    Section 3: Setting up SMUs in Clarius Model 4200A-SCS Source-Measure Unit (SMU) User's Manual Voltage List Sweep operation mode The Voltage List Sweep operation mode allows you to customize the voltage values for each step of the sweep. List sweeps allow you to make measurements only at selected forced voltages and currents.

  • Page 46: Voltage Step Operation Mode

    Model 4200A-SCS Source-Measure Unit (SMU) User's Manual Section 3: Setting up SMUs in Clarius An example of a log sweep is shown in the following figure. Figure 40: Example logarithmic sweep Voltage Step operation mode The Voltage Step operation mode increments through evenly-spaced, constant voltage steps over a range that you specify.

  • Page 47: Current Segment Sweep Operation Mode - Smu

    Section 3: Setting up SMUs in Clarius Model 4200A-SCS Source-Measure Unit (SMU) User's Manual Current Segment Sweep operation mode - SMU When you select the Current Segment Sweep operation mode, the test increments through a series of constant current steps. You can define the starting current and up to four stop-current points and four step-current points.

  • Page 48: Current Log Sweep Operation Mode - Smu

    Model 4200A-SCS Source-Measure Unit (SMU) User's Manual Section 3: Setting up SMUs in Clarius Figure 43: Example list sweep The current sweep generates parametric curve data that is recorded in the Analyze pane. Current Log Sweep operation mode - SMU The Current Log Sweep operation mode allows you to sweep over a large range and plot the measurements on a logarithmic scale.

  • Page 49: Current Step Operation Mode

    Section 3: Setting up SMUs in Clarius Model 4200A-SCS Source-Measure Unit (SMU) User's Manual Current Step operation mode The Current Step operation mode increments through evenly-spaced, constant current steps over a range that you specify. The time interval for each step is determined automatically by the time required to complete a sweep.

  • Page 50: Column Name (Measure Current)

    Model 4200A-SCS Source-Measure Unit (SMU) User's Manual Section 3: Setting up SMUs in Clarius Column Name (Measure Current) The name of the current measurement. This is the name that Clarius displays in the Analyze spreadsheet column for that measurement. If you do not define a name, Clarius assigns a name. The assigned name is a combination of the terminal label and I for current.

  • Page 51: Dual Sweep

    Section 3: Setting up SMUs in Clarius Model 4200A-SCS Source-Measure Unit (SMU) User's Manual The lowest allowable compliance is based on the load and the source value. For example, if you are sourcing 1 V to a 1 kΩ resistor, the lowest allowable current compliance is 1 mA (1 V/1 kΩ = 1 mA). Setting a compliance lower than 1 mA limits the source.

  • Page 52: Force Range (Source Range)

    Model 4200A-SCS Source-Measure Unit (SMU) User's Manual Section 3: Setting up SMUs in Clarius Force Range (Source Range) The SMU range that is used when forcing the voltage or current. You can select: • Best Fixed: The instrument selects a single fixed source range that accommodates all the source levels in the test.

  • Page 53: On Time

    Section 3: Setting up SMUs in Clarius Model 4200A-SCS Source-Measure Unit (SMU) User's Manual On Time Available when Pulse Mode is selected. The amount of time that the pulse is on (5 ms to 20 s). Overvoltage protection Overvoltage protection restricts the maximum voltage level that the instrument can source. It is in effect when either current or voltage is sourced.

  • Page 54: Points

    Model 4200A-SCS Source-Measure Unit (SMU) User's Manual Section 3: Setting up SMUs in Clarius Points The number of points that are measured. This value is calculated by Clarius using the information entered for the Start, Stop, and Step parameters, using the following equation: Power On Delay When a test is run, the SMUs power on in a specific sequence.
  • Page 55 Section 3: Setting up SMUs in Clarius Model 4200A-SCS Source-Measure Unit (SMU) User's Manual Pulse on and off times can be set from 5 ms to 20 s. The base voltage (or current) that can be set is dependent the present source range. More than one SMU in the test can be pulsing.

  • Page 56: Range (Measure Current)

    Model 4200A-SCS Source-Measure Unit (SMU) User's Manual Section 3: Setting up SMUs in Clarius Figure 48: Pulse Mode examples Range (Measure Current) The measure range determines the full-scale measurement span that is applied to the signal. It affects both the accuracy of the measurements and the maximum signal that can be measured. The current range options are: •...

  • Page 57: Report Status (Smu)

    Section 3: Setting up SMUs in Clarius Model 4200A-SCS Source-Measure Unit (SMU) User's Manual Report Status (SMU) When this option is selected, Clarius records measurement status information when the test executes. A column of the Analyze spreadsheet displays this information. Hover over a cell to review the information.

  • Page 58: Start (Step)

    Model 4200A-SCS Source-Measure Unit (SMU) User's Manual Section 3: Setting up SMUs in Clarius Start (step) The Start parameter is the current or voltage that is forced for the first step value. Start (sweep) The current or voltage source level at which the sweep starts. For a log sweep, the start value cannot be 0.

  • Page 59: Step (Voltage Sweep)

    Section 3: Setting up SMUs in Clarius Model 4200A-SCS Source-Measure Unit (SMU) User's Manual Step (voltage sweep) The current size of each step of the sweep. The current level changes in equal steps of this size from the start level to the stop level. A measurement is made at each source step (including the start and stop levels).

  • Page 60: Stop (Step)

    Model 4200A-SCS Source-Measure Unit (SMU) User's Manual Section 3: Setting up SMUs in Clarius Stop (step) The current or voltage that is forced for the last step value. Stop (sweep) The voltage or current source level at which the sweep stops. For a log sweep, the stop value cannot be 0 or the opposite polarity of the start value.

  • Page 61: Report Timestamps

    Section 3: Setting up SMUs in Clarius Model 4200A-SCS Source-Measure Unit (SMU) User's Manual Report Timestamps When this option is selected, every measurement in the Analyze sheet includes a timestamp. When this option is cleared, the timestamp is not included. The timestamp records the elapsed time for each measurement.

  • Page 62: Delay Factor

    Model 4200A-SCS Source-Measure Unit (SMU) User's Manual Section 3: Setting up SMUs in Clarius Figure 51: Timestamps when Clarius requires multiple readings for a measurement You can enable the timestamp for any of the measurement speeds. Delay Factor After applying a voltage or current, the instrument waits for a delay time before making a measurement.

  • Page 63: Filter Factor

    Section 3: Setting up SMUs in Clarius Model 4200A-SCS Source-Measure Unit (SMU) User's Manual The following table summarizes the Delay Factor settings. Speed Mode Delay Factor Fast Normal Quiet Custom 0 to 100 When entering a custom Delay Factor setting, consider the following: •...

  • Page 64: Auto A/D Aperture

    Model 4200A-SCS Source-Measure Unit (SMU) User's Manual Section 3: Setting up SMUs in Clarius Auto A/D Aperture When Speed is set to Custom and Auto A/D Aperture is selected, the instrument picks the optimum analog-to-digital (A/D) conversion time for most normal measurements. A/D Aperture Time If Custom Speed is selected and Auto A/D Aperture is cleared, you can specify the analog-to-digital (A/D) converter integration time that is used to measure a signal.

  • Page 65: Sweep Delay

    Section 3: Setting up SMUs in Clarius Model 4200A-SCS Source-Measure Unit (SMU) User's Manual When Sampling Mode is selected, all device terminals are set to a static operation mode, such as Open or Voltage Bias. Refer to Operation mode timing diagrams (on page 5-22) for additional detail.

  • Page 66: Disable Outputs At Completion - Smu

    Model 4200A-SCS Source-Measure Unit (SMU) User's Manual Section 3: Setting up SMUs in Clarius Disable outputs at completion - SMU If "Disable Outputs at Completion" is cleared, the SMU outputs remain at their last programmed levels when the test is completed. To prevent electrical shock that could cause injury or death, never make or break connections to the 4200A-SCS while the output is on.

  • Page 67: Compliance Exit-Condition Options

    Section 3: Setting up SMUs in Clarius Model 4200A-SCS Source-Measure Unit (SMU) User's Manual Figure 52: Select Output Values Compliance exit-condition options The compliance exit-condition options are available from the Test Settings pane when you select Exit Condition. When the source goes into compliance, you can choose the action that the system takes. You can select one of the following exit-condition options: •...

  • Page 68: Source-Measure Hardware

    Section 4 Source-measure hardware In this section: Source-measure units .............. 4-1 Source-measure hardware overview ........4-1 Basic SMU circuit configuration ..........4-2 SMU terminals and connectors ..........4-3 Source-measure unit (SMU) with 4200-PA overview ....4-5 Ground unit (GNDU) overview ..........4-12 Source-measure units This section provides information about the hardware and connections for the 4200-SMU, 4201-SMU, 4210-SMU, and 4211-SMU source-measure units and related instruments, including:...

  • Page 69: Basic Smu Circuit Configuration

    Section 4: Source-measure hardware Model 4200A-SCS Source-Measure Unit (SMU) User's Manual Figure 53: Source-measure hardware overview Basic SMU circuit configuration The basic SMU circuit configuration is shown in the following figure. The SMU is essentially a voltage or current source in series with a current meter, connected in parallel with a voltage meter. The voltage limit (V-limit) and current limit (I-limit) circuits limit the voltage or current to the programmed compliance value.

  • Page 70: Smu Terminals And Connectors

    Model 4200A-SCS Source-Measure Unit (SMU) User's Manual Section 4: Source-measure hardware Figure 54: Basic SMU source-measure configuration SMU terminals and connectors The locations and configuration of the SMU terminals are shown in the following figure. Basic information about these terminals is summarized below. Asserting the interlock allows the SMU and preamplifier terminals to become hazardous, exposing the user to possible electrical shock that could result in personal injury or death.

  • Page 71: Sense Lo Terminal

    Section 4: Source-measure hardware Model 4200A-SCS Source-Measure Unit (SMU) User's Manual The maximum allowed voltage between COMMON and chassis ground is ±32 V dc. Figure 55: 4200-SMU and 4210-SMU connectors SENSE LO terminal The SENSE LO terminal is a miniature triaxial connector used to apply the SMU SENSE LO signal to the DUT in a full-Kelvin (remote sense) application.

  • Page 72: Sense Terminal

    Model 4200A-SCS Source-Measure Unit (SMU) User's Manual Section 4: Source-measure hardware SENSE terminal The SENSE terminal is a miniature triaxial connector used to apply the SMU SENSE signal to the DUT in a remote-sense application when the preamplifier is not used. •...

  • Page 73: Basic Smu/Preamplifier Circuit Configuration

    Section 4: Source-measure hardware Model 4200A-SCS Source-Measure Unit (SMU) User's Manual Basic SMU/preamplifier circuit configuration The basic SMU and preamplifier circuit configuration is shown in the following figure. This configuration is similar to the SMU configuration discussed earlier, with the exception of the preamplifier, which adds low-current source-measure capabilities.

  • Page 74: Using Minimum Compliance

    Model 4200A-SCS Source-Measure Unit (SMU) User's Manual Section 4: Source-measure hardware Using minimum compliance The minimum compliance value is particularly applicable when measurement autorange is disabled. When measurement autorange is disabled, the compliance value cannot be set below the minimum value that is specified in the previous tables indicating 4200-PA compliance limits.

  • Page 75: Preamplifier Terminals And Connectors

    Section 4: Source-measure hardware Model 4200A-SCS Source-Measure Unit (SMU) User's Manual 4210-SMU or 4211-SMU with 4200-PA: In the following figure, the 1 A, 20 V and 100 mA, 200 V magnitudes are nominal values. The actual maximum output magnitudes of the 4210-SMU or 4211-SMU and 4200-PA are 1.05 A, 21 V and 105 mA, 210 V.
  • Page 76 Model 4200A-SCS Source-Measure Unit (SMU) User's Manual Section 4: Source-measure hardware Turn off the system and disconnect the power cord before connecting or disconnecting the preamplifier. Failure to do so may result in SMU or preamplifier damage, possibly voiding the warranty.

  • Page 77: Force Terminal

    Section 4: Source-measure hardware Model 4200A-SCS Source-Measure Unit (SMU) User's Manual FORCE terminal The FORCE terminal is a standard triaxial connector used as a return path for the SMU or preamplifier FORCE current. The center pin is FORCE, the inner shield is GUARD, and the outer shield is circuit COMMON.

  • Page 78: Sense Terminal

    Model 4200A-SCS Source-Measure Unit (SMU) User's Manual Section 4: Source-measure hardware SENSE terminal The SENSE terminal is a standard triaxial connector used to apply the ground unit SENSE signal to the DUT in a remote sense application. The center pin is SENSE, the inner shield is GUARD, and the outer shield is circuit COMMON.

  • Page 79: Ground Unit (Gndu) Overview

    Section 4: Source-measure hardware Model 4200A-SCS Source-Measure Unit (SMU) User's Manual Figure 62: Typical SMU COMMON connections schematic Ground unit (GNDU) overview The following topics describe: • Basic circuit configurations • Connectors Basic characteristics The ground unit, shown in the following figure, provides convenient access to circuit COMMON, which is the measurement ground signal shared by all installed 4200A-SCS instrumentation.

  • Page 80: Ground Unit Connections

    Model 4200A-SCS Source-Measure Unit (SMU) User's Manual Section 4: Source-measure hardware Figure 63: Ground unit (GNDU) connectors Ground unit connections The following figure shows how the various GNDU signals are related to the SMU signals. The GNDU FORCE signal is circuit COMMON. The GNDU SENSE terminal is connected to each SMU SENSE LO signal through an autosense resistor.

  • Page 81: Ground Unit Dut Connections

    Section 4: Source-measure hardware Model 4200A-SCS Source-Measure Unit (SMU) User's Manual Ground unit DUT connections The following figure shows the connections necessary to use the GNDU with a SMU to make full-Kelvin remote sense measurements. Similarly, the following figure includes the preamplifier. As shown in these figures, the GNDU FORCE signal provides the return path for SMU or preamplifier FORCE current.

  • Page 82: Ground Unit Terminals And Connectors

    Model 4200A-SCS Source-Measure Unit (SMU) User's Manual Section 4: Source-measure hardware Figure 66: Full-Kelvin preamplifier to ground unit connections Ground unit terminals and connectors Refer to Using the ground unit (on page 2-12) for the locations and configuration of the GNDU terminals.

  • Page 83: Sense Terminal

    Section 4: Source-measure hardware Model 4200A-SCS Source-Measure Unit (SMU) User's Manual SENSE terminal The SENSE terminal is a standard triaxial connector used to apply the ground unit SENSE signal to the DUT in a remote sense application. The center pin is SENSE, the inner shield is GUARD, and the outer shield is circuit COMMON.

  • Page 84: Source-Measure Concepts

    Section 5 Source-measure concepts In this section: Source-measure concepts ............5-1 Guarding .................. 5-1 Local and remote sensing ............5-5 Source or sink ................5-8 Source-measure considerations ..........5-12 Sweep concepts ..............5-19 Operation mode timing ............5-22 Source-measure concepts •...

  • Page 85: Guard Connections

    Section 5: Source-measure concepts Model 4200A-SCS Source-Measure Unit (SMU) User's Manual To avoid high voltage exposure that could result in personal injury or death, whenever the interlock of the 4200A-SCS is asserted, the FORCE and GUARD terminals of the SMUs and preamplifier should be considered to be at high voltage, even if they are programmed to a nonhazardous voltage current.

  • Page 86: Guarding Concepts

    Model 4200A-SCS Source-Measure Unit (SMU) User's Manual Section 5: Source-measure concepts Guarding concepts Guarding is especially important with high-impedance circuits. Consider the comparison of the unguarded and guarded circuits shown in the following figures. In both cases, FORCE is connected to DUT HI and COMMON is connected to DUT LO.

  • Page 87: Test Fixture Guarding

    Section 5: Source-measure concepts Model 4200A-SCS Source-Measure Unit (SMU) User's Manual Test fixture guarding GUARD used to drive the inner shields of triaxial connecting cables can be routed within test fixtures. Inside the test fixture, a triaxial cable can be used to extend the guard near to the DUT, and the guard can be connected to a guard plate or shield that surrounds the DUT.

  • Page 88: Local And Remote Sensing

    Model 4200A-SCS Source-Measure Unit (SMU) User's Manual Section 5: Source-measure concepts In the following figure, the driven GUARD is connected to the metal guard plate for the insulators. Since the voltage on either end of R is the same (0 V drop), no current can flow through the leakage resistance path.
  • Page 89 Section 5: Source-measure concepts Model 4200A-SCS Source-Measure Unit (SMU) User's Manual To use local sensing, connect only SMU FORCE and ground unit FORCE (COMMON) to the DUT, as shown in the following figure. Figure 73: Local sensing overview To use remote sensing, connect both SENSE and both FORCE terminals to the DUT as shown in the following figure.

  • Page 90: Local Sensing

    Model 4200A-SCS Source-Measure Unit (SMU) User's Manual Section 5: Source-measure concepts Local sensing Measurements made on devices with impedances above approximately 1 kΩ are generally made using the local sensing method, as shown in the following figure. The SMU test current is forced through the test leads and the DUT being measured, developing a voltage across the device (V The SMU then measures the voltage across the DUT (V ) through the same set of test leads.

  • Page 91: Remote Sensing

    Section 5: Source-measure concepts Model 4200A-SCS Source-Measure Unit (SMU) User's Manual Remote sensing The remote sensing method shown in the following figure is generally preferred for measurements on low-impedance DUTs. With this configuration, the test current I is forced through the DUT through one set of test cables, while the voltage across the DUT is measured through a second set of sense cables.

  • Page 92: 4200-Smu And 4201-Smu Source Or Sink

    Model 4200A-SCS Source-Measure Unit (SMU) User's Manual Section 5: Source-measure concepts For example, if a second SMU that is sourcing +12 V is connected to the first SMU that is programmed for +10 V, sink operation for the first SMU occurs in the second quadrant (source +V and measure −I).

  • Page 93: 4210-Smu Or 4211-Smu Source Or Sink

    Section 5: Source-measure concepts Model 4200A-SCS Source-Measure Unit (SMU) User's Manual 4210-SMU or 4211-SMU source or sink In the following figure, the 1A, 20 V and 100 mA, 200 V magnitudes are nominal values. The actual maximum output magnitudes of the 4210-SMU and 4211-SMU are 1.05 A, 21 V and 105 mA, 210 V. The boundaries are not drawn to scale.

  • Page 94: 4200-Smu And 4201-Smu Sink Boundaries

    Model 4200A-SCS Source-Measure Unit (SMU) User's Manual Section 5: Source-measure concepts 4200-SMU and 4201-SMU sink boundaries Nominal 4200-SMU and 4201-SMU boundaries are shown in the following figure. Note that actual boundaries are 210 V at 10.5 mA or 21 V at 105 mA. Figure 79: 4200-SMU or 4201-SMU with a 4200-PA operating boundaries 4200A-SMU-900-01 Rev.

  • Page 95: 4210-Smu And 4211-Smu Sink Boundaries

    Section 5: Source-measure concepts Model 4200A-SCS Source-Measure Unit (SMU) User's Manual 4210-SMU and 4211-SMU sink boundaries Nominal 4210-SMU and 4211-SMU sink boundaries are shown in the following figure. Actual boundaries are 210 V at 105 mA or 21 V at 1.05 A. Figure 80: 4210-SMU or 4211-SMU with a 4200-PA operating boundaries Source-measure considerations When configured to source current (I-Source), the SMU functions as a high-impedance current source...

  • Page 96: Source V, Measure I Or V

    Model 4200A-SCS Source-Measure Unit (SMU) User's Manual Section 5: Source-measure concepts Figure 81: Source I, measure V configuration Source V, measure I or V When configured to source voltage (V-Source) as shown in the following figure, the SMU functions as a low-impedance voltage source with current limit capability and can measure current (I-Meter) or voltage (V-Meter).

  • Page 97: Measure Only (V Or I)

    Section 5: Source-measure concepts Model 4200A-SCS Source-Measure Unit (SMU) User's Manual Measure only (V or I) The next figures show the configurations for using the SMU exclusively as a voltmeter or ammeter. For both of these configurations, use local sensing. For measure V, set the voltage compliance higher than the measured voltage.

  • Page 98: I-Source Operating Boundaries

    Model 4200A-SCS Source-Measure Unit (SMU) User's Manual Section 5: Source-measure concepts I-Source operating boundaries Limit lines are boundaries that represent the operating limits of the SMU for a certain quadrant of operation. The operating point can be anywhere inside (or on) these limit lines. The limit line boundaries for the other quadrants are similar.

  • Page 99: I-Source Operation Examples

    Section 5: Source-measure concepts Model 4200A-SCS Source-Measure Unit (SMU) User's Manual I-Source operation examples The following figures show operation examples for resistive loads that are 2 kΩ and 8 kΩ, respectively. For these examples, the SMU is programmed to source 10 mA and limit (compliance) 40 V. The SMU is sourcing 10 mA to the 2 kΩ...

  • Page 100: V-Source Operating Boundaries

    Model 4200A-SCS Source-Measure Unit (SMU) User's Manual Section 5: Source-measure concepts Notice that as resistance increases, the slope of the DUT load line increases. As resistance approaches infinity (open output), the SMU sources virtually 0 mA at 40 V. However, as resistance decreases, the slope of the DUT load line decreases.

  • Page 101: V-Source Operation Examples

    Section 5: Source-measure concepts Model 4200A-SCS Source-Measure Unit (SMU) User's Manual Figure 90: SMU voltage source limit lines V-Source operation examples The following figures show operation examples for resistive loads that are 20 kΩ and 8 kΩ, respectively. For these examples, the SMU is programmed to source 50 V and limit 5 mA. The SMU is sourcing 50 V to the 20 kΩ...

  • Page 102: Source I Measure I And Source V Measure V

    Model 4200A-SCS Source-Measure Unit (SMU) User's Manual Section 5: Source-measure concepts Notice that as resistance decreases, the slope of the DUT load line increases. As resistance approaches infinity (open output), the SMU will source about 50 V at 0 mA. However, as resistance decreases, the slope of the DUT load line increases.

  • Page 103: Source-Delay-Measure Cycle

    Section 5: Source-measure concepts Model 4200A-SCS Source-Measure Unit (SMU) User's Manual Source-delay-measure cycle During each source-delay-measure cycle, the following occurs: 1. The source output level is set. 2. There is a wait for the source delay. 3. The measurement is made. The delay phase of the cycle, which is programmed by software, allows the source and external circuitry to settle before the measurement is made.
  • Page 104 Model 4200A-SCS Source-Measure Unit (SMU) User's Manual Section 5: Source-measure concepts Figure 94: Sweep waveforms A source-delay-measure cycle is performed on each step (or point) of the sweep. One measurement is made at each step. The time spent at each step depends on how the source-delay-measure cycle is configured, such as the sweep delay setting.

  • Page 105: Operation Mode Timing

    Section 5: Source-measure concepts Model 4200A-SCS Source-Measure Unit (SMU) User's Manual Operation mode timing The following figure shows source-measure timing for a test system using three SMUs. It shows basic timing between the sweep, step, and bias operation modes. Figure 95: Sweeping Mode timing diagram 5-22 4200A-SMU-900-01 Rev.

  • Page 106: Sampling Mode Timing

    Model 4200A-SCS Source-Measure Unit (SMU) User's Manual Section 5: Source-measure concepts The timing elements act as follows: • Hold Time (HT): The sweep graph shows two sweeps that correspond to the two steps shown directly above in the step graph. There is a hold time at the start of each sweep. The hold time is a global setting, so it is the same for all SMUs in the test system.
  • Page 107 Section 5: Source-measure concepts Model 4200A-SCS Source-Measure Unit (SMU) User's Manual A range-dependent delay (D) is automatically applied by a SMU before each measurement to allow for source settling. All SMUs in the test system are synchronized. Therefore, the delay time applied by the most-delayed SMU is the delay time applied by all SMUs.

  • Page 108: Optimizing Smu Measurements

    Section 6 Optimizing SMU measurements In this section: Introduction ................6-1 Making stable measurements with SMUs ........ 6-1 Low-current measurements............6-4 Interference ................6-11 Introduction This section includes information on improving measurement stability, making low-current measurements, and reducing interference. Making stable measurements with SMUs The following topics discuss various considerations when making stable measurements, including single-SMU stability, multiple-SMU stability, and avoiding oscillation.

  • Page 109: Multiple Smu Stability Considerations

    Section 6: Optimizing SMU measurements Model 4200A-SCS Source-Measure Unit (SMU) User's Manual Multiple SMU stability considerations Using two or more SMUs to test an active device, such as a field-effect transistor (FET) or bipolar junction transistor (BJT), can increase system instability. The following figure shows an example of BJT characterization curves measured under stable conditions.

  • Page 110: Eliminating Oscillations

    Model 4200A-SCS Source-Measure Unit (SMU) User's Manual Section 6: Optimizing SMU measurements Eliminating oscillations In general, oscillations can be classified as high-frequency (100 kHz through 200 MHz) or low frequency (below 100 kHz). The measures needed to eliminate oscillations depend on which type of the oscillation is occurring.

  • Page 111: Low-Current Measurements

    Section 6: Optimizing SMU measurements Model 4200A-SCS Source-Measure Unit (SMU) User's Manual To avoid oscillations for a FET, try the following actions: • Set (Drain SMU current measure range) = (Source SMU current measure range) • If necessary, set both SMUs to autorange. •...

  • Page 112: Leakage Currents

    Model 4200A-SCS Source-Measure Unit (SMU) User's Manual Section 6: Optimizing SMU measurements Leakage currents Leakage currents are generated by high-resistance paths between the measurement circuit and nearby voltage sources. These currents can considerably degrade the accuracy of low-current measurements. Cable leakage currents are a common source of leakage. Typically, insulation resistance between conductors in the type of triaxial cables supplied with the SMUs and preamplifiers is approximately 1 PΩ...
  • Page 113 Section 6: Optimizing SMU measurements Model 4200A-SCS Source-Measure Unit (SMU) User's Manual Offset currents The preamplifier has a small current, known as the input offset current, that flows at all times. As shown in the figure below, the input offset current adds to the measured current so that the SMU measures the sum of the two currents.
  • Page 114 Model 4200A-SCS Source-Measure Unit (SMU) User's Manual Section 6: Optimizing SMU measurements Triboelectric effects Triboelectric currents are generated by charges created by friction between a conductor and an insulator. Free electrons rub off the conductor and create a charge imbalance that causes the current flow.

  • Page 115: Voltage Burden

    Section 6: Optimizing SMU measurements Model 4200A-SCS Source-Measure Unit (SMU) User's Manual Contamination and humidity Error currents can arise from electrochemical effects when ionic chemicals create weak batteries between two conductors on a circuit board. For example, if epoxy-printed circuit boards are not thoroughly cleaned of etching solution, flux, or other contamination, the contamination can generate currents of a few nanoamps between conductors.

  • Page 116: Noise And Source Impedance

    Model 4200A-SCS Source-Measure Unit (SMU) User's Manual Section 6: Optimizing SMU measurements Voltage burden for the SMUs is less than or equal to the offset specifications of the source voltage. Figure 101: Effects of voltage burden Noise and source impedance Noise can seriously affect sensitive current measurements.

  • Page 117: Cable Capacitance

    Section 6: Optimizing SMU measurements Model 4200A-SCS Source-Measure Unit (SMU) User's Manual Cable capacitance Without guarding, the effects of cable capacitance would adversely affect the settling time when sourcing current. The rise time of the source depends on the total shunt capacitance at its output. For a high-impedance load, even a small amount of cable capacitance can result in long rise times.

  • Page 118: Interference

    Model 4200A-SCS Source-Measure Unit (SMU) User's Manual Section 6: Optimizing SMU measurements Interference Forms of interference that can degrade measurement integrity include electrostatic interference, radio-frequency interference, and ground loops. Electrostatic interference Electrostatic interference occurs when an electrically charged object is brought near an uncharged object, thus inducing a charge on the previously uncharged object.

  • Page 119: Ground Loops And Other Smu Grounding Considerations

    Section 6: Optimizing SMU measurements Model 4200A-SCS Source-Measure Unit (SMU) User's Manual Ground loops and other SMU grounding considerations Ground loops, which occur when more than one point in a test system is connected to safety (earth) ground, can create error signals that cause erratic or erroneous performance. The configuration shown in the following figure shows a ground loop that is created by connecting 4200A-SCS signal COMMON and DUT LO to safety (earth) ground.

  • Page 120: Make I-V Measurements On A Solar Cell

    Section 7 Make I-V measurements on a solar cell In this section: Introduction ................7-1 Equipment required ..............7-1 Device connections ..............7-2 Setting up measurements in the Clarius software ....7-4 Introduction This example shows how to use a 4200-SMU, 4201-SMU, 4210-SMU, or 4211-SMU instrument to perform a forward-biased voltage sweep on a solar cell in a 4-wire configuration.

  • Page 121: Device Connections

    Section 7: Make I-V measurements on a solar cell Model 4200A-SCS Source-Measure Unit (SMU) User's Manual Device connections Connect your preamplifier or SMU output terminals to the solar cell in a 4-wire configuration. This provides the best measurement accuracy and eliminates the effects of the resistance of the test leads and unwanted voltage drops.

  • Page 122: Connect The 4200A-Scs To The Dut

    Model 4200A-SCS Source-Measure Unit (SMU) User's Manual Section 7: Make I-V measurements on a solar cell Connect the 4200A-SCS to the DUT The following figures show the 4200A-SCS rear-panel connections for the methods mentioned in the Device connection schematic (on page 7-2) topic. You can make the connections shown in the following figures using four 4200-TRX-2 or 4200-MTRX-2 triaxial cables.

  • Page 123: Setting Up Measurements In The Clarius Software

    Section 7: Make I-V measurements on a solar cell Model 4200A-SCS Source-Measure Unit (SMU) User's Manual Setting up measurements in the Clarius software This section demonstrates how to set up the 4200A-SCS to perform an I-V sweep on a solar cell. The fwd-ivsweep test measures current at each step of a user-configured voltage sweep.

  • Page 124: Search For And Select A Test

    Model 4200A-SCS Source-Measure Unit (SMU) User's Manual Section 7: Make I-V measurements on a solar cell Search for and select a test To search for and select the test: 1. Select Tests. 2. In the Filters pane, select Solar Cell. Figure 109: Use filters to select the fwd-ivsweep test 3.

  • Page 125: Configure The Test

    Section 7: Make I-V measurements on a solar cell Model 4200A-SCS Source-Measure Unit (SMU) User's Manual Configure the test To configure the test: 1. In the project tree, select the fwd-ivsweep solar cell I-V test in the project tree. 2. Select Configure. Figure 111: Configure highlighted 3.
  • Page 126 Model 4200A-SCS Source-Measure Unit (SMU) User's Manual Section 7: Make I-V measurements on a solar cell 4. In the Test Settings pane, adjust the Measure Settings and Test Mode as needed. Figure 113: Test Settings pane The Formulator is also in the Test Settings pane. If you select the Formulator in the Test Settings pane, the Formulator dialog box appears as shown in the figure below.

  • Page 127: Run The Test

    Section 7: Make I-V measurements on a solar cell Model 4200A-SCS Source-Measure Unit (SMU) User's Manual Figure 114: Formulator dialog box This test calculates V , and other device parameters. See the Electrical Characterization of Photovoltaic Materials and Solar Cells with the 4200A-SCS Parameter Analyzer application note for details on Formulator calculations.

  • Page 128: Analyze The Test Results

    Model 4200A-SCS Source-Measure Unit (SMU) User's Manual Section 7: Make I-V measurements on a solar cell Analyze the test results You can select Analyze when you run the project to view test results in real time. Figure 116: Analyze highlighted You can also use the View icons in the upper-right of the center pane to display the sheet, graph, or sheet and graph.

  • Page 129: Additional Tests

    Section 7: Make I-V measurements on a solar cell Model 4200A-SCS Source-Measure Unit (SMU) User's Manual The sheet displays the results with the voltage and current data labeled AnodeV and AnodeI, respectively. The formulas calculated in the Formulator are shown in the right-most columns. They include the maximum power (PMAX), open circuit voltage (VOC), short circuit current (ISC), and fill factor (FF).
  • Page 130 Specifications are subject to change without notice. All Keithley trademarks and trade names are the property of Keithley Instruments. All other trademarks and trade names are the property of their respective companies. Keithley Instruments Corporate Headquarters • 28775 Aurora Road • Cleveland, Ohio 44139 • 440-248-0400 • 1-800-833-9200 • tek.com/keithley 07/2020...

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